UNIVERSITY    OF    CALIFORNIA     AGRICULTURAL    EXPERIMENT  STATION 

«•««•■«.«•«-     nr-     •  *«,»..*«...—..__  BENJ.    IDE    WHEELER,    PRESIDENT 

COLLEGE  OF  AGRICULTURE  THOMAS  FQRSYTH  HUNT    Dean  _  d,rector 

BERKELEY  h.  e.  van  norman,  vice-director  and  dean 

University  Farm  School 

CIRCULAR  No.  170 

September,  1917 


FERTILIZING  CALIFORNIA  SOILS 
FOR  THE  1918  CROP1 

By  C.  B.  LIPMAN 


GENERAL   CONSIDERATIONS 

The  statements  made  below  with  reference  to  the  proper  systems 
of  fertilization  which  can  be  followed  on  California  soils  during  the 
next  two  or  three  years  will  be  almost  entirely  limited  to  the  phase 
of  fertilization  connected  with  the  use  of  commercial  fertilizers.  For 
that  reason  the  nitrogen,  phosphoric  acid,  and  potash  situations  will 
be  treated  chiefly. 

In  connection  with  all  of  the  considerations  on  the  use  of  fer- 
tilizers on  California  soils  either  during  the  period  of  war  or  during 
other  times  when  high  prices  ©btain,  it  must  be  remembered  that  the 
ruling  factor  is  the  economic  one.  During  the  period  of  the  war, 
the  chief  desideratum  is  maximum  yields,  inasmuch  as  the  food  sup- 
ply of  this  country  and  that  of  her  allies  is  bound  to  be  limited  even 
if  maximum  yields  are  obtained.  If,  therefore,  the  producer  of  crops 
can  make  no  profit,  but  also  incurs  no  loss,  by  the  use  of  fertilizers, 
but  can  make  every  acre  of  his  land  produce  more  in  a  given  season 
by  the  use  of  such  fertilizers,  it  would  seem  to  be  his  clear  duty  as 
a  patriot  to  employ  fertilizers  in  his  cropping  operations.  But  an- 
other side  to  the  situation  appears  in  time  both  of  war  and  of  peace 
when  high  prices  for  crops  reign.  That  is,  that  while  in  times  of 
moderate  or  low  prices  it  is  unprofitable,  even  though  the  crop  be 
increased  thereby,  to  use  fertilizers  on  certain  classes  of  crops,  the 
practice  of  fertilization  will  prove  highly  profitable  when  prices  for 
products  are  high.  So  far  as  California  farmers  are  concerned,  this 
situation  is  particularly  true  of  the  cereals  and  other  ordinary  field 
crops. 

1  It  is  assumed  in  this  circular  that  the  reader  understands  that  fertilizer 
treatment  of  soils  is  merely  a  supplementary  measure  in  the  handling  of  soils, 
and  that  it  must  fall  far  short  of  the  best  results  if  proper  tillage,  planting,  and 
other  operations  are  not  insured,  particularly  in  the  case  of  annual  crops. 


THE    CHIEF    NEEDS    OF    CALIFORNIA    SOILS 

It  is  a  truism  that  nitrogen  and  organic  matter  are  the  most  im- 
portant factors  in  the  fertility  of  agricultural  soils  the  world  over. 
This  applies  nowhere  with  such  great  force,  however,  as  in  the  case  of 
the  arid  soils  of  California  and  in  that  of  similar  arid  soils  elsewhere. 
Everywhere  the  pre-eminent  factor  in  soil  fertility,  the  question  of 
the  nitrogen  supply,  because  of  the  great  scarcity  of  that  element 
w^ch  characterizes  arid  soils,  is  far  more  acute,  and  far  more  one 
of  present  moment  in  California  than  elsewhere.  With  the  nitrogen 
question  is  indissolubly  linked  the  organic  matter  question,  since  the 
organic  matter  supplies  most  of  the  nitrogen  upon  which  successful 
crop  growth  depends,  and  since  moreover  certain  essential  trans- 
formations of  the  nitrogen  in  soils  depend  on  the  proper  supply  of 
the  organic  matter.  It  is,  therefore,  urged  with  all  the  force  which 
we  can  command  that  the  producer  of  crops  in  California  recognize 
first  and  foremost  that  his  problem  in  the  maintenance  of  fertility  in 
California  soils  lies  chiefly  in  supplying  his  soils  with,  and  maintain- 
ing therein,  as  large  a  supply  of  nitrogen  as  he  can  with  financial 
profit,  or  even  without  loss. 

HOW    TO    SUPPLY    ORGANIC    MATTER 

Without  going  into  detail  on  the  questions  of  methods  for  supply- 
ing organic  matter  which  have  been,  br  will  be,  discussed  in  other 
experiment  station  publications,  it  may  be  briefly  stated  that  the 
following  means  are  available  for  adding  to  the  organic  matter  supply 
of  California  soils.  One  or  more  of  the  methods  recommended  may 
have  to  be  used  in  order  to  obtain  the  best  results. 

1.  The  use  of  all  available  farm  manure,  including  all  that  can 
be  purchased  at  low  rates. 

2.  The  use  in  orchards  and  vineyards  in  the  fall  of  the  year  and 
on  summer  fallowed  grain  land  during  the  fallow  year,  of  all  avail- 
able straw  of  whatever  kind,  including  that  which  can  be  purchased 
at  very  low  rates. 

3.  The  use  of  green  manuring  crops,  preferably  the  leguminous 
crops,  grown  throughout  the  winter  and  spring  and  plowed  under 
about  April  first.  The  choice  for  these  crops  should  be  made  from 
the  following,  preference  being  given  in  the  order  named:  Melilotus 
indica,  vetch,  and  bur  clover. 

4.  Weeds  from  neglected  fields,  beet  tops,  other  similar  plant 
refuse,  and  prunings  from  trees  and  vines  may  with  good  effect  be 
incorporated  with  soil,  especially  in  the  fall  of  the  year. 


In  addition  to  the  use  of  all  these  manures,  it  should  be  constantly 
borne  in  mind  that  conservation  of  organic  matter  in  the  soil  is  fully 
as  important  as  the  addition  of  organic  matter  thereto.  For  that 
reason  it  is  strongly  urged  that  on  orchard  and  vineyard  lands,  wher- 
ever possible,  straw  mulches2  be  employed  as  protective  coverings  to 
the  soil.  They  preserve  the  organic  matter  of  the  soil  in  two  ways, 
first  by  preventing  excessive  oxidation  of  the  organic  matter  which 
results  from  cultivation  with  its  attendant  large  introduction  of 
oxygen  and  increased  temperatures,  and,  second,  by  the  addition  of 
a  portion  thereof  to  the  soil.  Even  if  such  mulching  cannot  be  fol- 
lowed for  more  than  a  period  covering  the  summer  months,  say  from 
April  15  to  November  1,  it  will  be  of  great  advantage.  The  best 
mulches,  owing  to  their  high  nitrogen  contents,  are,  of  course,  the 
legume  straws  like  bean  straw,  pea  straw,  coarse  alfalfa  hay,  and  simi- 
lar substances.  In  their  absence,  however,  the  grain  straws  like 
oats,  barley,  wheat  and  rice  may  be  used.  Rice  hulls  will  also  serve 
as  valuable  mulching  material  and  where  a  plentiful  supply  of  farm 
manure  is  a\ailable,  it  may  also  be  used  for  that  purpose. 

NITROGEN 

Our  investigations  on  the  nitrogen  content  of  California  soils  have 
shown  that  in  the  truly  arid  parts  of  the  state,  the  great  majority  of 
soils  contain  less  than  .05  per  cent  of  nitrogen.  This  means  a  maxi- 
mum of  2000  pounds  per  acre  foot,  or  6000  pounds  in  the  upper  three 
feet.  Only  a  small  portion  of  the  total  nitrogen  contained  in  soils 
can  become  available  for  use  by  plants,  in  the  growing  season,  by  its 
proper  transformation  through  bacterial  agencies,  and  an  ordinary 
barley  crop  will  probably  remove  sixty  pounds  of  nitrogen  per  acre. 
The  nitrogen  which  we  can  count  on  for  plant  growth  is  properly 
nitrified  only  in  the  top  eighteen  inches  of  soil,  hence  it  can  be  readily 
appreciated  that  the  supply  of  the  important  element  in  question  is 
very  limited  and  from  the  point  of  view  of  soil  fertility  is  the  chief 
factor  to  be  taken  into  consideration  at  this  time. 

The  Form  of  Nitrogen  to  Use. — Not  only  is  the  total  nitrogen  sup- 
ply very  limited  in  most  of  our  soils,  but  owing  to  the  lack  of  organic 
matter  and  the  poor  moisture  conditions  for  the  greater  part  of  the 
year,  the  bacterial  flora  upon  which  we  depend  for  rendering  the 
nitrogen  of  soils  available  are  less  efficient  than  the  bacteria  in  soils 
of  the  eastern  states  where  rain  falls  the  year  around.     This  is  par- 

2  It  is  to  be  borne  in  mind  in  connection  with  the  use  of  straw  mulches  that 
there  is  always  danger  of  fire  and  precautions  must  be  taken  to  prevent  it.  Leav- 
ing every  other  middle  or  every  third  middle  unmulched  will  minimize  the  danger 
considerably. 


4 

ticularly  true  insofar  as  the  transformation  of  organic  nitrogen  into 
nitrates  is  concerned.  On  the  other  hand,  some  forms  of  commercial 
fertilizer  nitrogen  have  been  found  to  stimulate  these  bacteria  to  a 
relatively  high  efficiency  and  at  the  same  time  are  quickly  made 
available  to  crops.  While  it  is  impossible  to  make  general  statements 
of  absolute  value  for  every  soil  in  the  state,  it  is,  nevertheless,  true 
that  certain  general  rules  for  the  use  of  nitrogenous  fertilizers  in 
California  may  be  formulated  on  the  basis  of  our  studies.  They  may 
be  stated  briefly  as  follows  as  regards  the  form  of  nitrogen  to  employ : 

1.  In  the  soils  of  the  San  Joaquin  Valley  and  in  those  of  the  south- 
ern valleys  of  California,  including  the  southern  coast  valleys,  the 
southern  portion  of  the  Sacramento  Valley,  and  in  other  places  where 
the  rainfall  is  below  sixteen  inches  per  annum,  it  appears  that  a 
high  grade  inorganic  nitrogenous  fertilizer  is  to  be  preferred  to  the 
organic  forms  and  especially  where  quick  results  are  desired.  The 
best  representative  of  the  high  grade  nitrogenous  fertilizers  for  the 
class  of  soils  under  consideration  here  is  sulphate  of  ammonia.  It  may 
be  used  on  all  crops  in  the  case  of  these  soils.  Nitrate  of  soda  may  be 
used  also  in  the  case  of  grain  soils  with  good  effect.  Our  investiga- 
tions have  shown  that  both  nitrate  of  soda  and  sulphate  of  ammonia 
are  very  effective  in  increasing  enormously  the  crop  of  grain  on  nitro- 
gen-poor soils,  such  as  those  here  concerned ;  and  in  the  case  of  orchard 
soils  that  sulphate  of  ammonia  is  to  be  preferred  to  nitrate  of  soda, 
and  particularly  on  the  heavier  soils  of  the  citrus  growing  districts. 

2.  On  soils  of  the  northern  and  northwestern  counties  of  the  state, 
including  a  considerable  portion  of  the  north  half  of  the  Sacramento 
Valley  and  in  some  of  our  more  southern  coast  valleys,  together  with 
a  few  more  isolated  and  limited  districts  all  over  the  state,  in  which 
the  soils  contain  more  than  the  usual  quantity  of  organic  matter  and 
of  nitrogen,  the  high  grade  organic  nitrogenous  fertilizers  will  serve 
as  well.  In  these  regions  they  are  superior  to  the  inorganic  nitro- 
genous fertilizers,  like  sulphate  of  ammonia  and  nitrate  of  soda.  On 
this  class  of  soils,  therefore,  it  is  urged  that  high  grade  nitrogenous 
fertilizers,  like  dried  blood,  high  grade  tankage  and  fish  guano,  be 
given  first  choice,  that  the  high  grade  inorganic  nitrogenous  fertilizers, 
like  nitrate  of  soda  and  sulphate  of  ammonia  be  given  second  choice, 
and  that  the  low  grade  organic  nitrogenous  fertilizers  like  cotton  seed 
meal,  steamed  bone  meal,  and  garbage  tankage,  be  given  third  choice. 
Other  considerations  bearing  on  the  choice  of  fertilizers  will  be  given 
below. 

Amounts  of  Nitrogenous  Fertilizers  to  Employ. — In  the  case  of 
barley,  wheat,  oats,  rye,  and  field  crops  of  relatively  low  value  per 


acre,  it  is  recommended  that  on  the  first  class  of  soils  above  mentioned, 
125  pounds  of  nitrate  of  soda  per  acre  or  100  pounds  of  sulphate  of 
ammonia  per  acre  be  applied.  For  the  same  crops  on  the  second 
class  of  soils  it  is  recommended  that  the  preference  be  given  to  dried 
blood  or  high  grade  tankage,  used  as  follows :  Dried  blood,  200  pounds 
per  acre ;  high  grade  tankage,  250  pounds  per  acre. 

For  orchard  and  vineyard  crops  on  the  first  class  of  soil,  sulphate 
of  ammonia  is  recommended  in  amounts  varying  from  300  to  500 
pounds  per  acre.  The  applications  need  not  be  made  every  year. 
Nitrate  of  soda,  it  seems,  at  the  present  time,  best  to  recommend 
against  for  citrus  orchards  in  southern  California,  since  some  investi- 
gations seem  to  point  to  bad  effects  on  trees,  resulting  from  its  use 
for  several  years.  Low  grade  organic  nitrogenous  fertilizers  may  be 
used  with  good  effect  in  the  case  of  the  soils  of  the  first  class,  but  not 
with  as  good  effect  on  soils  of  the  second  class,  nor  with  as  good  effect 
as  sulphate  of  ammonia.  When  dried  blood  and  high  grade  tankage 
are  used  on  orchard  soils,  however,  they  should  be  applied  at  the  rates, 
respectively,  of  500  to  800  pounds,  and  600  to  1000  pounds  per  acre. 

When  and  How  to  Apply  Nitrogenous  Fertilizers. — Our  investiga- 
tions have  not  as  yet  indicated  with  exactitude  the  most  propitious 
time  for  the  application  of  nitrogenous  fertilizers  for  crops.  They 
have,  however,  given  some  hints  in  that  direction  which  are  considered 
valuable  and  the  following  statements  may  be  made  as  a  result.  When 
application  of  the  fertilizer  in  question  is  determined  in  the  case  of 
winter  grain,  nitrate  of  soda  or  sulphate  of  ammonia  should  be 
applied  as  a  top  dressing  on  the  standing  grain  in  the  month  of  Feb- 
ruary wherever  possible.  In  the  case  of  spring  grain,  these  fertilizers 
may  be  applied  between  the  middle  of  March  and  the  middle  of  April, 
especially  if  there  is  promise  of  further  rain  for  that  season.  Dried 
blood,  high  grade  tankage,  or  similar  material  should  be  applied  prior 
to  the  preparation  of  land  for  the  grain  crop  and  plowed  or  cultivated 
in.  In  the  case  of  orchard  crops,  it  is  best  to  consider  the  irrigated, 
and  the  unirrigated,  as  well  as  the  deciduous  and  the  citrus  orchards 
separately.  In  citrus  orchards,  it  is  best  to  apply  sulphate  of  am- 
monia in  from  three  to  five  applications,  employing  about  one  pound 
per  tree  per  application,  in  the  months  of  February,  March,  and  April, 
or  similarly  from  January  to  May.  If  organic  nitrogenous  fertilizers 
be  used,  the  application  should  be  made  in  the  fall  or  early  winter 
and  cultivated  or  plowed  in,  preferably  at  one  application.  If  plow- 
ing or  cultivating  is  done  later  in  the  spring,  it  will  be  advisable  to 
put  off  the  application  of  these  fertilizers  until  the  month  of  Febru- 
ary or  March.     In  the  case  of  irrigated  deciduous  orchards,  the  same 


rules  will  apply  as  in  the  case  of  the  citrus  orchard,  except  that  the 
minimum  rather  than  the  maximum  application  should  be  employed 
and  the  application  made  in  the  spring  months  exclusively. 

On  the  unirrigated  deciduous  orchards  and  vineyards,  the  appli- 
cation of  these  fertilizers  should  be  made  not  later  than  the  first  of 
March  in  the  case  of  sulphate  of  ammonia  and  nitrate  of  soda, 
and  preferably  a  month  earlier,  in  the  case  of  organic  nitrogenous 
fertilizers. 

The  Cost  of  Nitrogenous  Fertilizers. — The  economics  of  the  fer- 
tilizer situation  is  fully  as  important  as  all  other  considerations  and 
perhaps  more  so.  It  is  for  that  reason  that  the  general  comment 
regarding  the  use  of  fertilizers  in  the  present  emergency  was  made 
in  the  introductory  remarks  above.  In  addition  thereto,  however, 
some  observations  need  to  be  made  at  this  point.  Wherever  the  use 
of  certain  forms  of  nitrogenous  fertilizers  is  not  specifically  discour- 
aged, the  first  consideration  in  the  choice  of  a  fertilizer  should  be  the 
cost  at  which  a  certain  number  of  pounds  of  nitrogen  may  be  obtained. 
Therefore,  even  though,  for  example,  100  pounds  of  sulphate  of 
ammonia  per  acre  is  preferred  for  a  barley  crop  in  southern  Califor- 
nia or  in  the  San  Joaquin  Valley,  to  165  pounds  of  dried  blood, 
which  contains  about  the  same  amount  of  nitrogen,  the  latter  should 
be  chosen  if  that  quantity  of  dried  blood  can  be  obtained  for  less 
money  than  the  quantity  of  sulphate  of  ammonia  mentioned.  The 
opposite  will  be  true  where  dried  blood  or  the  class  of  materials  it 
represents  is  to  be  preferred  to  the  inorganic  nitrogenous  fertilizers 
as  above  explained.  The  freight  charges  on  the  fertilizers  to  a  given 
ranch  must  also  be  taken  into  consideration  when  the  calculations 
above  referred  to  are  made,  so  that  the  actual  cost  of  the  fertilizer  to 
the  farmer,  including  the  cost  of  application  or  incorporation  with 
the  soil  should  be  completely  computed  before  the  choice  of  a  fertilizer 
is  made.  It  is  remarked  further  that  the  amounts  of  fertilizers  recom- 
mended for  use,  especially  for  grain  and  field  crops,  are  often  chosen 
because  of  the  economics  of  the  situation  and  not  because  larger 
amounts  might  not  produce  larger  crops.  It  is  actually  true  that 
larger  amounts  of  sulphate  of  ammonia  than  100  pounds  per  acre 
will  produce  larger  grain  crops  than  the  amount  just  mentioned,  but 
with  the  income  from  an  acre  of  grain  or  other  field  crops  it  may  not 
be  possible  to  make  larger  applications  of  this  material  pay. 

It  is  difficult  to  state  for  the  use  of  our  readers  the  prices  of  the 
fertilizers  in  question,  for  the  reason  that  they  are  subject  to  constant 
change  and  because  fertilizer  materials  have  become  particularly 
valuable  during  the  period  of  the  war.  At  the  present  writing, 
nitrate  of  soda  may  be  obtained  from  $90  to  $100  per  ton  and  sulphate 
of  ammonia  at  about  $130  per  ton.  Another  item,  therefore,  to  take 
into  consideration  when  making  the  calculations  above  indicated  is 
the  amount  being  paid  per  pound  for  nitrogen  in  a  ton  of  a  given 
fertilizer.  Since  the  analysis  of  the  fertilizer  is  always  given,  the 
number  of  pounds  of  nitrogen  per  100  pounds  or  per  ton  and  the 


cost  of  a  pound  of  nitrogen  are  easily  determined.  In  this  manner, 
two  or  more  fertilizers  can  be  compared  in  price  very  easily.  Where 
fertilizers  are  sold  on  the  so-called  "unit"  basis,  the  latter  means 
merely  that  a  unit  stands  for  1  per  cent  of  a  ton,  or  twenty  pounds. 
Thus,  if  nitrogen  sells  for  $5  per  unit,  it  means  that  for  every  twenty 
pounds  of  nitrogen  in  a  ton  of  a  given  fertilizer  $5  is  paid,  or  in  other 
words,  nitrogen  costs  25  cents  a  pound.  The  same  applies  to  the 
purchase  of  other  fertilizer  ingredients  like  phosphoric  acid  and 
potash. 

This  experiment  station  stands  ready  at  any  time  to  advise  people 
regarding  the  choice  of  a  fertilizer  among  several  offered  if  the  crop 
and  location  are  stated  and  the  price  and  analyses  of  the  fertilizers 
are  given. 

PHOSPHORIC   ACID 

In  general,  it  appears  to  be  true  that  phosphate  fertilizers  cannot 
at  the  present  time  be  made  to  yield  profitable  returns  on  the  arid 
soils  of  California.  While  the  amounts  of  phosphoric  acid  in  our 
soils  are  not  large,  and,  in  general,  about  the  same  as  those  of  eastern 
soils,  the  greater  depth  of  our  soils,  which  encourages  at  least  slightly 
deeper  feeding  of  plants  than  that  characteristic  of  plants  on  eastern 
soils,  appears  to  make  it  possible  for  crops  to  obtain  the  necessary 
phosphoric  acid  which  they  require  for  maximum  growth  at  the  pres- 
ent time.  It  is  particularly  emphasized  in  this  connection  that  this 
is  merely  a  general  rule  and  like  all  rules  has  its  prominent  exceptions. 
During  the  period  of  the  war,  however,  it  seems  pretty  safe  to  dis- 
courage the  use  of  phosphate  fertilizers  for  any  of  our  field  crops 
except  as  specifically  recommended  below.  In  the  case  of  our  orchards 
also,  with  few  exceptions,  it  seems  undesirable  and  unprofitable  now 
to  employ  phosphoric  acid  fertilizers. 

There  are,  however,  certain  soil  conditions  in  California  in  which 
the  application  of  phosphates  will  pay  and  some  instances  in  which 
no  paying  crop  can  be  grown  without  their  use.  These  conditions  are 
very  largely  limited  to  the  tule  and  overflow  soils  of  the  delta  region 
of  the  Sacramento  and  San  Joaquin  rivers,  in  which,  while  the  total 
amount  of  phosphoric  acid  may  sometimes  be  fairly  large,  there  is 
only  a  small  quantity  which  is  available  for  plant  growth.  The  use 
of  from  300  to  1000  pounds  of  superphosphate  per  acre,  depending 
on  the  value  of  the  crops  grown,  has  in  several  instances  been  shown 
to  be  productive  of  excellent  results.  In  all  of  the  potato,  asparagus, 
bean,  and  vegetable  lands  of  our  delta  regions  which  consist  chiefly 
of  organic  matter,  it  is  recommended  that  superphosphate  or  some 
similar  form  of  readily  available  phosphoric  acid  be  employed  for 
the  increase  of  the  crop.  It  is  to  be  remembered  here  again  that  even 
if  no  great  profit  is  to  accrue  from  the  employment  of  phosphoric  acid 
fertilizers  under  such  circumstances,  it  is  the  patriotic  duty  of  the 
owner  of  such  land  to  increase  the  crop  output  per  acre,  which  he  can 
do  in  this  case  by  the  use  of  the  fertilizer  recommended,  certainly 
without  loss,  and  in  practically  all  cases  with  considerable  profit. 

There  are  some  lands  in  the  San  Joaquin  Valley,  and  particularly 


8 

those  of  the  blow-sand  type  in  the  vicinity  of  Atwater,  Livingston, 
Ripon,  and  similar  regions,  where  it  may  pay  to  use  phosphate  fer- 
tilizers owing  to  the  rather  unusually  low  content  of  available  phos- 
phoric acid  which  characterizes  those  soils.  Experimental  data  with 
respect  to  this  matter  are  too  meager  at  the  present  time  to  justify 
our  making  any  recommendations  for  the  use  of  phosphate  fertilizers 
to  the  soils  in  question,  though  it  is  believed  that  on  annual  field 
crops  profitable  returns  will  result  from  the  use  of  phosphate  fer- 
tilizer on  these  soils  provided  the  nitrogen,  which  is  needed  there 
even  more  than  the  phosphoric  acid,  is  employed  as  above  recom- 
mended. 

In  general,  superphosphate  may  be  purchased  at  approximately 
$18  per  ton,  thus  making  it  a  relatively  low-priced  fertilizer. 

POTASH 

With  the  possible  exception  of  the  delta  soils,  which  are  spoken 
of  in  connection  with  the  phosphoric  acid  problem,  it  seems  quite 
certain  that  potash  fertilizers  cannot  be  made  to  return  profitable 
yields  on  arid  California  soils.  In  addition,  it  also  seems  true  that 
the  size  of  the  crop  may  not  be  materially  increased  by  the  use  of 
potash  fertilizers,  even  without  profit.  Taking  these  facts  together 
with  the  extraordinarily  high  prices  which  are  now  charged  for  potash 
fertilizers  ($400  to  $500  per  ton  of  high  grade  sulphate  or  chloride 
of  potash),  it  seems  necessary  to  recommend  at  this  time  that  potash 
fertilizers  be  not  employed  during  the  period  of  the  war  on  California 
soils.  The  high  prices  for  potash  fertilizers  are  due  to  the  fact  that 
the  chief  source  of  supply  of  the  world 's  potash  has  been  at  the  Stass- 
furt  mines  in  Germany,  which,  are,  of  course,  at  the  present  time, 
closed  so  far  as  the  world,  other  than  the  Central  Empires,  is 
concerned.  Various  sources  of  potash  are  being  developed  in  this 
country,  but  have  not  as  yet  reached  the  large  output  which  is  neces- 
sary to  lower  the  present  high  prices  for  potash. 

On  the  delta  lands  or  similar  soils  consisting  chiefly  of  organic 
matter,  and  on  some  of  the  badly  leached  soils  of  our  northern  and 
northwestern  counties  where  excessive  rainfall  is  obtained  every  year, 
potash  fertilizers  may  be  used  to  advantage  if  a  cheap  form  like  that 
of  wood  ashes  is  obtainable.  Considerable  amounts  of  wood  ash 
result  from  the  burning  over  of  many  of  our  timber  lands  following 
logging  operations.  These  supplies  of  wood  ashes  will  be  a  valuable 
asset  to  the  leached  soils  mentioned  above  and  if  they  can  be  obtained 
for  use  on  these  classes  of  soils  at  low  rates,  can  undoubtedly  be  used 
there  with  profit  in  crop  production  and  in  some  limited  instances 
may  even  be  instrumental  in  making  a  crop  where  otherwise  prac- 
tically none  could  be  produced.  Other  materials  may  be  used  in 
lieu  of  the  wood  ashes  under  the  circumstances  named,  if  the  cost  of 
their  production  is  not  very  great;  for  example,  the  ash  of  kelp,  of 
weeds,  of  brush,  of  tule  grasses,  and  of  other  organic  materials  con- 
taining potash  will  also  serve  acceptably  if  they  can  be  obtained  at 
relatively  low  prices,  which  necessarily  will  vary  in  accordance  with 
the  percentage  of  potash  contained  in  the  particular  kind  of  ash. 


